Voice Examination in Patients with Decreased High Pitch after Thyroidectomy

Abstract

Decreased high pitch after thyroidectomy due to injury of the external branch of superior laryngeal nerve (EBSLN) may be a critical, especially to professional voice users. The author studied the usefulness of VRP (voice range profile) and MDVP (multi-dimensional voice program) to evaluate patients who have decreased high pitch after thyroidectomy. A study was performed with 58 females and 9 males who underwent voice assessment between January 2008 and June 2009. The patients were classified as the group of female with no decreased high pitch (group A, n=52), decreased high pitch (group B, n=6) and the group of male with no decreased high pitch (group C, n=9). VRP and laryngeal electromyogram (EMG) was performed in group B. The preoperative frequency range of group A and B were statistically not different. In Group B, the result of VRP showed that the frequency range was 443.11±83.97, 246.67±49.41, 181.37±80.13Hz showing significant decrease after the surgery compared to that of the preoperative result. (P<0.05) In addition, the intensity range was 22.25±2.87, 15.25±2.22, 16.25±2.63dB respectively showing significant postoperative decrease. (P<0.05) EMG of the cricothyroid muscle of group B showed decreased potential with 3 patients, normal potential in 2, and the other patient refused to take the examination. In group A and C, the result of VRP revealed no significant difference between the preoperative and postoperative result. VRP is a noninvasive, quick, and practical test to demonstrate decreased frequency range visually and helps to evaluate EBSLN injury in patient with thyroidectomy.